My guess is that the barrel looks like that because it has to, or so my imagination told me:

The original Florrtex barrels broke down when in close proximity to the beam over time.

The newer Monatomic barrels are silver in color and do not accept paints or dyes.

While it’s customers originally balked at this (Many had “better looking” Florrtex models with unsafely decaying barrels that wanted this look preserved) but eventually it was decided that the weapon performed optimally with the newer materials and aesthetics were grudgingly put aside for better functionality in this series.

Later models incorporated similar looking metals to blend the styling, but this one is sought out among collectors because of the change that occured mid-series.

Models with the original black Florrtex barrels are extremely rare and are generally only seen in museums and in the possession of very wealthy collectors.

See? There’s always an explanation if you give me enough time to think of one.

if it makes you feel better I’ll slap some wood grain stickers on it for you, and some brass spray paint. hehehehe
I saw that done to a few items recently on some amateur SP sites and kinda laughed to myself. It’s like kids that put Carbon fibre stickers all over their cars, or farbon cibre as I like to call it.